Model-based Fault Diagnosis Of The 6-speed Automatic Transmission(6AT)

With the rapidly development of the world economy,science and technology,Today,Automobile industry has entered a stage of speedily development in the world.Hydraulic Automatic Transmission as a core component of the car,its functionality and reliability would directly affect the vehicle's power performance and security.Therefore,research on fault diagnosis technology of the automatic transmission,not only do can objectively evaluate its operation performance,but also can predict the potential failure.The methodology and techniques in this dissertation will help to reduce automatic transmission failures and improve vehicle safety and reliability,which has great theoretical significance and practical value.This dissertation relies on the U.S.-China Clean Energy Research Center Project "Research on the fault diagnosis and intelligent prediction techniques of automobile ",where the study of fault diagnosis concerning the 6-speed automatic transmission are discussed especially.In this dissertation,the ability of Fault Detection and Isolation(FDI)for the hydraulic torque converter and shifting actuator is analysed by utilizing the methodology of fault diagnosis based on Structural Analysis(SA).Design some robust and stable residuals are used to validating the availability abvoe mentioned the methodology.The detail work are as follows,Firstly,the basic structure and function of Toyota A760 E 6-speed automatic transmission are systematical introduced.By employing the Failure Modes and Effects Analysis(FMEA)method,failure modes,failure effects and causes are analyzed.The hazard degree of different system failures are evaluated with Risk Priority Number(RPN),as a result,the critical failures of the analyzed systems are achieved.Fault trees are established by using the Fault Tree Analysis(FTA),which explicitly represent the logic relationship between system failures,subsystem failures and the component failures.Secondly,By analysing the features and properties of the critical failures,then failure variable parameters are introduced according to the major types and characterization forms of the critical failures.In order to obtain the failure models respectively,Establish the mathematical model of hydraulic torque converter and shifting actuator combine with failure variable parameters.The FDI is analysed by utilizing the DulmageMendelsohn(DM)decomposition.Then,some sequential residuals based on Analytical Redundancy Relations(ARR)are designed according to Minimal Structurally Over-determined sets(MSO sets).Finally,The simulation model of sequential residuals are designed,and then insert the virtual fault,the model of FDI system is established by using Simulink simulation software.To verify the feasibility and availability of fault diagnosis method based on SA,Choose a fixed value as the threshold value of the residuals,the fault is true or not by judging the residual value is more than the corresponding threshold,and then comparing the diagnostic results with the virtual fault.